JPH0821359B2 - Focused ion beam device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a focused ion beam apparatus for irradiating a material with a focused ion beam, and in particular, an optical axis of the ion beam is arbitrary with respect to an axis orthogonal to the surface of the material. The present invention relates to a focused ion beam device that can be tilted at an angle.

[Prior Art] In the field of semiconductors and the like, ion implantation technology has been used in which predetermined ions are made to collide with a material and penetrate into the material, thereby controlling the physical properties of the material or creating a new material. There is.

When performing such ion implantation, usually, there are cases where the ions are implanted at once in the entire material or a wide area, or when ions are implanted in a predetermined minute portion. The former uses a non-focused ion beam and the latter uses A focused ion beam is used.

Now, the latter apparatus using a focused ion beam is called a focused ion beam apparatus, which focuses an ion beam from an ion source and irradiates the ion beam to an arbitrary position on a material such as a silicon wafer. Equipment,
Such a focused ion beam apparatus is used for resist exposure for the purpose of drawing a minute pattern, because it can irradiate ions at extremely minute locations instead of the ion implantation height.

However, when the material is ion-implanted as described above, when the ions are irradiated perpendicularly to the surface of the material, the ions are deeply implanted without colliding with the atoms of the material. Such a phenomenon is called a channel effect, but it is necessary to minimize such a channel effect unless a deep ion implantation is intentionally performed. Therefore,
By irradiating the material surface with the ion beam obliquely,
The inn is made to collide with the material atom so that it stops near the surface of the material.

Therefore, in the focused ion beam apparatus for performing the resist exposure for the purpose of the ion implantation and the drawing of a minute pattern, the present inventor, when switching to the ion implantation mode,
A measure for obliquely irradiating the ions was considered.

As the first countermeasure, as shown in FIG. 4 (a),
The material M is made horizontal, and the ion beam focused by the focusing lens L is tilted at an angle θ (7 °) with respect to the optical axis O by the oblique irradiation deflector consisting of the deflectors Da and Db in the upper and lower stages to irradiate the material. To do. However, in a focused ion beam device, a high acceleration voltage of about 150 KV is usually used,
In order to tilt the ion beam accelerated by an accelerating voltage of about 150 KV by 7 °, a large deflection voltage of about ± 20 KV is required, and this measure is impractical.

The second measure is as shown in FIG. 4 (b).
The material M is tilted at an angle θ (7 °) with respect to the optical axis O, and the material is irradiated with the ion beam focused by the focusing lens L.
However, there is a limit to the deflection width of the ion beam due to the relationship of deflection distortion, and in a focused ion beam device, normally, when the ion beam is deflected within a predetermined range, the stage on which the material is placed is moved in the horizontal direction by a predetermined amount, Further, the step of deflecting the ion beam is repeated (referred to as a step-and-repeat method), so that the height of the beam irradiation point on the material changes greatly each time the stage moves. Therefore, it is necessary to provide a dynamic focus adjustment mechanism to correct the focus in the optical axis direction. Further, due to such a height change of the beam irradiation point, the deflection width of the ion beam must be adjusted every time the stage is moved. Therefore, in the case of such measures, the beam control system becomes complicated and the operation becomes troublesome.

[Problems to be Solved by the Invention] An object of the present invention is to provide a focused ion beam apparatus equipped with a novel tilting mechanism that solves the problems of the respective countermeasures.

In the focused ion beam apparatus capable of performing resist exposure and ion implantation for the purpose of drawing a minute pattern, the present inventor has further devised a countermeasure capable of solving the problems of each of the above countermeasures, and when switching to the ion implantation mode. I considered a new measure that does not require an unrealistic deflection voltage and that does not require focus correction in the optical axis direction or ion beam deflection width correction for each stage movement due to the height change of the ion beam irradiation point. .

[Means for Solving the Problems] A focused ion beam apparatus of the present invention is an ion beam generating means, a focusing lens for focusing an ion beam from the ion beam generating means, and a shot of the ion beam at a predetermined position on a material. A casing provided with a deflector for
In a focused ion beam apparatus including a chamber in which the material is placed, in order to tilt the casing in a vacuum-proof manner so that the optical axis of the ion beam is tilted at an arbitrary angle with respect to an axis perpendicular to the surface of the material. The mechanism of

[Embodiment] FIG. 2 is a schematic view of a focused ion beam apparatus shown as an embodiment of the present invention.

In the figure, 1 is an ion source, 2 is a focusing lens, 3X and 3Y are X-direction and Y-direction deflectors, 4 is a stage, 5 is a material, 6 is a controller, 7X and 7Y are DA converters, and 8 is a stage. It is a movement drive mechanism. Incidentally, 9 is a casing, and 10 is a chamber.

FIGS. 1 (a) and 1 (b) show the main part of the present invention, showing the connection between the housing 9 and the chamber 10 and the housing tilting mechanism. Incidentally, FIG. 1 (b) is a view of FIG. 1 (a) seen from a direction 90 degrees away from the vertical direction on a horizontal plane including the direction perpendicular to the paper surface. Chamber 10 as shown
Bearings 11A and 11B are attached to the upper lid 180 degrees apart from each other, and shafts 12A and 12B that penetrate the bearings 11A and 11B are attached to the casing 9. Further, brackets 13A and 13B are attached to the casing at positions 90 degrees apart from the shafts 12A and 12B, respectively.
The push screws 14A and 14B screwed into A and 13B are the chambers.
Hitting the top lid of 10. The lower portion of the casing 9 and the flange portion of the upper lid of the chamber 10 are vacuum-resistant connected by a bellows 15, for example, by brazing.

Now, in the case of performing resist exposure for the purpose of drawing a minute pattern with such a focused ion beam apparatus,
Both push screws 14A and 14B are tightened to the same degree so that the optical axis of the ion beam is parallel to the axis perpendicular to the material surface (horizontal plane). That is, the casing 9 is kept in a state where it is not tilted at all. In this state, the control device 6 sends the position data to be irradiated to the DA converters 7X and 7Y. Therefore,
The ion beam from the ion source 1 is focused on the surface of the material by the focusing lens 2, and the focused ion beam is applied to a predetermined position on the resist coated on the material to perform a predetermined resist exposure.

When performing ion implantation with such a focused ion beam device, first, the push screw 14A is placed on the upper lid of the chamber 10 so that the optical axis of the ion beam is inclined by 7 degrees with respect to the axis perpendicular to the material surface. The push screw 14B is rotationally moved by a predetermined amount in a direction away from the surface, and then the pushing screw 14B is rotationally moved by a predetermined amount toward the upper lid surface of the chamber 10, and the casing 9 is tilted based on the movement. In addition, according to the tilt angle of the ion beam optical axis with respect to the axis orthogonal to the material surface, these push screws are used as a reference (the position of the push screw when the tilt angle of the casing is 0 degree).
Therefore, how much the rotational movement should be performed is obtained in advance. Further, in this manner, when the casing 9 is tilted so that the optical axis of the ion beam is tilted by 7 degrees with respect to the axis orthogonal to the material surface, the intersection of the optical axis orthogonal to the material surface and the material surface is centered. Since it is not tilted but tilted about the axis connecting the central axis of the shaft 12A and the central axis of 12B, the irradiation position of the ion beam on the material corresponds to the distance between the tilt centers ( Although it deviates by a certain amount), this deviation is known in advance, so in conjunction with switching to the ion implantation mode,
The control device 6 automatically moves the length stage corresponding to this shift in the horizontal direction. Further, although the ion beam is not focused on the material due to the inclination, the deviation of the focus is known in advance.
The control device 6 automatically controls the focusing lens 2 in association with the switching to the mode so that the material 5 is focused. It should be noted that any of these automatic adjustments may be performed once when switching to the ion implantation mode. Then, the ion beam from the ion source 1 is focused on the material surface by the focusing lens 2, the focused ion beam is irradiated to a predetermined position on the material, and predetermined ion implantation is performed.

FIG. 3 shows another example of the mechanism capable of inclining the casing, in which the central portion 16 of the upper lid of the chamber 10 is formed in a hemispherical shape, and the lower portion of the casing 9 is along the hemispherical portion. The lower part of the casing is formed into an umbrella shape so that it slides, and supports 17A and 17B are attached to the upper lid of the chamber 10 so as to be 180 degrees apart from each other, and a damper 18 is inserted between the support 17A and the casing. The pushing screw 19 is screwed into the support 17B so that the tip end contacts the casing 9. An O-ring 20 is inserted between the lower part of the casing which is in contact with the central portion 16 of the upper lid of the chamber 10 and the sealing property between them is maintained. In such a mechanism, the housing can be tilted at an angle based on the rotational movement amount of the push screw 19. In the second embodiment, if the upper part of the hemisphere is formed so that the center of the sphere is located on the surface of the material, the stage position and the focus can be adjusted as described above when the ion implantation mode is switched. It can be omitted.

However, as a countermeasure for solving the problems of the countermeasures shown in FIGS. 4 (a) and 4 (b), the present inventor mounts the stage S on the optical axis O as shown in FIG. Placed material M
At the same time, the inventors also considered a measure to incline the chamber C in which the material M is arranged with respect to the casing K so that the angle θ becomes an angle θ (7 °). With this measure, an unrealistic deflection voltage is not required, and even if the stage moves, the height of the beam irradiation point on the material does not change. Ion beam deflection width correction is also unnecessary. However, according to this measure, when the whole is not flat in the direction perpendicular to the direction of gravity, the gravity is not evenly applied to the entire chamber, so that the chamber becomes unstable. Therefore, a mechanism for stabilizing the chamber is needed. In addition, a mechanism is required to prevent the stage in the chamber from moving due to tilting. Also, the operation of those mechanisms is cumbersome. Therefore, this measure is not feasible for a focused ion beam apparatus that performs mode switching of resist exposure for drawing a minute pattern.

EFFECTS OF THE INVENTION The present invention is provided with a mechanism for inclining the casing in a vacuum-proof manner so that the optical axis of the ion beam is inclined at an arbitrary angle with respect to the axis perpendicular to the material surface. Even if the housing is tilted when injecting, like the conventional measures,
No unrealistic large deflection voltage is needed. Also, it is not necessary to perform focus correction in the optical axis direction each time the stage is moved, and readjustment of the deflection width of the ion beam is not necessary.
The beam control system is not complicated and the operation is not troublesome.

[Brief description of drawings]

1 (a) and 1 (b) are views showing an embodiment of a main part of the present invention, FIG. 2 is a schematic view of a focused ion beam device shown as an embodiment of the present invention, and FIG. 3 is a book. FIG. 4 shows another embodiment of the essential part of the invention, FIGS. 4 (a) and 4 (b) are used for explaining the conventional countermeasure, and FIG. 5 is a view for solving the conventional countermeasure. It shows other measures taken. 1 ... Ion source, 2 ... Focusing lens 3X, 3Y ... X-direction, Y-direction deflector 4 ... Stage, 5 ... Material 6 ... Control device 7X, 7Y ... DA converter 8 ... Stage movement Drive mechanism 9 …… Cylinder, 10 …… Chamber 11A, 11B …… Bearings 12A, 12B …… Shaft 13A, 13B …… Bracket 14A, 14B …… Push screw 15 …… Bellows 16 …… Chamber top center part 17A , 17B ... Support 18 ... Damper, 19 ... Push screw

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Shinji Matsui, 34, Miyukigaoka, Tsukuba, Ibaraki, NEC Research Laboratories (72) Yukinori Ochiai, 34, Miyukigaoka, Tsukuba, Ibaraki, Japan In-house (72) Inventor Tadatoshi Nozaki 4-1-1, Miyazaki, Miyamae-ku, Kawasaki-shi, Kanagawa Optoelectronics Research Laboratories, Nihon Denki Co., Ltd. (72) Inventor Hiroshi Sawaraki 3-1-2 Musashino, Akishima-shi, Tokyo Within JEOL Ltd. (56) Reference JP 59-43520 (JP, A) JP 59-184443 (JP, A)

Claims (1)

[Claims] 1. A casing including an ion beam generating means, a focusing lens for focusing the ion beam from the ion beam generating means, and a deflector for shooting the ion beam at a predetermined position on a material, and In a focused ion beam apparatus provided with a chamber in which a material is arranged, for tilting the casing in a vacuum-proof manner so that the optical axis of the ion beam is tilted at an arbitrary angle with respect to an axis perpendicular to the material surface. Focused ion beam device characterized by having a mechanism.